A phrase used by people so insecure about their sexuality that they feel the need to unnecessarily reinforce their heterosexuality--usually after saying something that most people wouldn't even associate with being "gay."
Hey man, good game.
Thanks. Love you, man. No homo.
Didn't think you were, but thanks for clearing that up. Didn't care either way.
I totally like Glee, but no homo.
Wait, so watching Glee means someone's gay? And you think a two-word, slang phrase will convince people otherwise if that's true?
No, dude, that's just wait people say.
You're an idiot.